Oil free compressors are used to compress gasses, in particularly air, for example for the medical technique, for pneumatic control or for the food industry. Medical use comprises, for example, driving drills for dental work, for water and air cleaning or for apparatus for artificial respiration. In the food industry oil free compressed air is used, for example, as drying air for packing machines or for bread dough fermentation. General technical use comprises, for example, for letter sorting apparatus, for the aeration of galvanic and chemical bathes and aquariums, for the pneumatic control of machine tools and other machines, for film coating or for ventilation of computers.